The present invention relates to an inverter apparatus including heating components and cooling fans, and more particularly to an inverter apparatus wherein cooling fans are replaceable.
Inverter apparatuses which are power converters are equipped with a printed-circuit board on which a control circuit and a power supply circuit are mounted, a main circuit including semiconductor elements, a cooling fin for the semiconductor elements, etc. as well as cooling fans for cooling these components. The cooling fans are required to be replaceable, and various mounting structures therefor have been proposed (see Japanese Laid-Open Patent Publication (Kokai) No. 2005-64046, for example).
FIG. 8 is an exploded perspective view showing how cooling fans are mounted in such a conventional inverter apparatus. FIG. 8 illustrates the construction of a fan unit case that houses the cooling fans. In this fan unit case, a plurality of cooling fans 101 are fixed to a sheet-metal mounting plate 102 by screws 103. The mounting plate 102 is provided with screws, not shown, so as to fix wires for supplying power to the cooling fans 101.
FIG. 9 is an exploded perspective view showing how cooling fans are mounted in another conventional inverter apparatus. As is the case with FIG. 8, FIG. 9 illustrates the construction of a fan unit case. In this fan unit case, a plurality of cooling fans 101 is fixed to a plastic mounting plate 104 by screws 103. The mounting plate 104 is provided with screws 105, not shown, so as to fix wires for supplying power to the cooling fans 101.
FIG. 10 is an external perspective view showing the conventional inverter apparatus as mentioned above. This inverter apparatus is configured as an integral-type inverter unit. A front cover 111 is fixed to the inverter main by screws 112, and a fan unit case that houses cooling fans is disposed inside the inverter unit.
FIGS. 11 and 12 are perspective views showing how to replace the cooling fans of the conventional inverter apparatus. In replacing the cooling fans, the screws 12 are unscrewed to open the front cover 111 (see FIG. 10), so that the fan unit case inside the inverter unit is exposed. Next, the screws that fix the wires for supplying power to the cooling fans 101 and the screws 113 that fix the fan unit case are unscrewed. The fan unit case 115 is then pulled forward (i.e. in a direction indicated by the arrow in FIG. 12) to replace the cooling fans 101.
New cooling fans 101 are housed following the above described removal steps in reverse. Specifically, the fan unit case 115 housing the cooling fans 101 is put back into the inverter unit, then the wires are fixed by the screws, and the fan unit case 115 is fixed by the screws 113. The front cover 111 is then fixed to the inverter main body by the screws 112. It should be noted that the above-mentioned components are screwed and unscrewed using predetermined tools such as drivers.
The conventional converter apparatuses constructed as described above, however, are expensive since a large number of components are required to satisfy a plurality of required functions, such as maintaining strength, fixing the cooling fans, and preventing bypass of cooling air.
Accordingly, a large amount of time is required since a large number of locations have to be screwed. For replacing cooling fans, screws have to be unscrewed using tools so as to open the front cover, and also, the fan unit case itself have to be pulled out since the fan unit case is fixed to the inside of the inverter unit by the screws.
For this reason, the conventional converter apparatuses have the problem that the replacement of cooling fans is complicated and time-consuming, and it requires a large amount of time and also have the problem that screws are mistakenly dropped. Also, when the fan unit case is pulled out, dust accumulated on the cooling fans for many years of usage falls into the inverter unit, which necessitates cleaning, and in some cases, causes an insulation failure or ignition. Further, since the cooling fans themselves are disposed away from holes in a lattice pattern formed in the uppermost surface (i.e. ceiling surface) of the inverter unit, the efficiency of the cooling fans is decreased due to a significant pressure drop of exhaust air.
It is an object of the present invention to provide an inverter apparatus that can make it easier to replace cooling fans, reduce the number of components, enhance cooling efficiency, and secure high reliability.
Further objectives and advantages of the invention will be apparent from the following description of the invention.